<?php 

$arr = array(
		'df'=>'sdfs',
		'ADfg'=>'sdfs',
		'RT'=>'sdfs',
		'dfgfd'=>'sdfs',
		'dfdA'=>array(
			'dfgf'=>'sdfs',
			'ADDFfg'=>'sdfs',
			'RTfgfg'=>'sdfs',
			'Adfgfd'=>array(
				'dfgf'=>'sdfs',
				'ADDFfg'=>'sdfs',
				'RTfgfg'=>'sdfs',
				'Adfgfd'=>'sdfs',
				)
		)
		);

var_dump($arr);


function Lower($arr){
	foreach ($arr as $k => $v) {
		echo $res = strtolower($k);
		if($k!=$res){
			$arr[$res]=$v;
			unset($arr[$k]);
		}
		if(is_array($v)){
			$arr[$res] = Lower($v);
		}
		
	}
	return $arr;
}


$newArr = Lower($arr);
var_dump($newArr);








 ?>